Optimum allocations test plans for Accelerated Life Test Plan

Minitab evaluates the resulting test plans and displays the best plans with respect to minimizing the standard error of the parameter of interest. By default, Minitab displays three test plans. The first best optimum allocations test plan is the one with the smallest variance.

Minitab also displays the second and third best optimum allocations of test units. If little difference exists in the standard error of the parameter of interest across test plans, choose the plan that would yield more failures or is the least expensive to execute.

Example output

1st Best “Optimum” Allocations Test Plan Test Percent Percent Sample Expected Stress Failure Alloc Units Failures 85 100 63.3333 63 63 105 100 3.9583 4 4 125 100 32.7083 33 33 Standard error of the parameter of interest = 0.0123437


For the capacitor data, the allocation of 100 units that minimizes the variance of the 1000-hour reliability is:
  • Test 63 units at 85 degrees; all 63 are expected to fail
  • Test 4 units at 105 degrees; all 4 are expected to fail
  • Test 33 units at 125 degrees; all 33 are expected to fail

The estimated standard error of the 1000-hour reliability is 0.0123437.

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